And I'm Melissa Block. The president of Ukraine signed a trade agreement with the European Union today. It positions his country toward closer economic ties with Europe. Russia fiercely opposed the pact and said the move would have serious consequences for Ukraine's struggling economy. NPR's Corey Flintoff has this report from Moscow.

COREY FLINTOFF, BYLINE: President Petro Poroshenko joined the leaders of two other former Soviet republics, Georgia and Moldova, in signing association agreements with the EU. He said the deal was the culmination of seven years' work.

(SOUNDBITE OF ARCHIVED RECORDING)

PRESIDENT PETRO POROSHENKO: I think this is one of the most historic days after getting independence. And I think that we can use this opportunity to modernize the country. The only thing we need for that is peace and security.

FLINTOFF: But Russian leaders warned that the deal could be costly in terms of lost trade privileges with Russia. Ukraine currently pays no duties on the goods it exports to Russia. But that will likely change. There was more evidence of Russian anger about the deal in the form of statements that seemed designed to cast doubt on the legitimacy of the Ukrainian government. Russia's President Putin reverted to some of the rhetoric he was using before Ukraine's presidential election.

(SOUNDBITE OF ARCHIVED RECORDING)

PRESIDENT VLADIMIR PUTIN: (Through translator) The anti-constitutional coup in Kiev is pushing an artificial choice on the Ukrainian people, either Europe or Russia. It forced the society to split into a painful confrontation.

FLINTOFF: One of Putin's senior advisors, Sergei Glazyev, you know went much further in this interview with the BBC.

(SOUNDBITE OF ARCHIVED RECORDING)

SERGEI GLAZYEV: Europe is trying to push Ukraine to sign this agreement by force. They organized a military coup in Ukraine. They helped Nazis to come in power. Now in Ukraine, we have the clear Nazi government.

FLINTOFF: A Kremlin spokesman later said that Glazyev's views were not those of the Russian government. But his statements were widely reported in state-run media. EU leaders said they wouldn't impose new sanctions on Russia now, but that they had plans ready for punishing Russia if it doesn't take measures to stem the flow of weapons and fighters to the separatists in Eastern Ukraine. Separatist leaders met today in Donetsk, with mediators from Kyiv, including former President Leonid Kuchma. One of the participants was the Oleg Tsaryov, the self-styled speaker of the Supreme Council of Novorossiya, or New Russia, the separatist name for a union of the self-declared republics. He said there's an agreement to extend the current ceasefire by 72 hours.

(SOUNDBITE OF ARCHIVED RECORDING)

OLEG TSARYOV: (Through translator) We consider it right to prolong the cease-fire, but it needs to be implemented in reality and not just on paper.

FLINTOFF: Late today the government had not confirmed that the ceasefire has been extended. Each side has accused the other of repeatedly violating the ceasefire, a problem that's compounded by the fact that the separatist leadership doesn't seem to have full control over all the armed groups. This is Mark Etherington, a leader of the observer mission from the Organization for Security and Cooperation in Europe.

MARK ETHERINGTON: It's not accurate to describe these people as a homogenous group. It is a patchwork of shifting allegiances, some almost futile.

FLINTOFF: Separatists released four of Etherington's OSCE observers today after holding them hostage for almost a month. But four of his other observers, held by a different group, still remain captive. Corey Flintoff, NPR News, Moscow. Transcript provided by NPR, Copyright NPR.